STUDY

Mid-phase movements of © by IAAF 23:2; 39-43, 2008 Tyson Gay and Asafa Powell in the 100 metres at the 2007 World Championships in Athletics

By Akira Ito, Koji Fukuda, Kota Kijima

ABSTRACT AUTHORS This study examines the running move- Akira Ito, PhD, is a Professor at the Osaka ments of two of the fastest sprinters in University of Health and Sport Sciences, history, Tyson Gay (USA) and former Osaka, Japan, and a member of the Scien- 100m world record holder Asafa Powell tific Committee of the Japan Association (JAM). They were filmed at the 60m mark of Athletics Federations. in the 100m final at the 2007 IAAF World Koji Fukuda and Kota Kijima work with Championships in Athletics, where they Prof Ito at the Osaka University of Health placed first (9.85) and third (9.96) respec- and Sport Sciences. tively. The data obtained were analysed and compared to past data in order to determine the characteristics of both sprinters and identify points of advice for required to run at top speed, the winner of the aspiring athletes and coaches. The event normally receives the greatest accolades parameters covered are step frequency of all the athletes at a major championship. The and step length, recovery leg movement most important element for success is maxi- and support leg movement. The landing mum running velocity, though a fast reaction distance for Gay and Powell is compara- time after the start signal and quick accelera- ble to 11 sec 100m performers and both tion are also important. World-class male continue to bend the knee of the support sprinters reach their maximum velocity at leg during the support phase. The authors’ about 70-80m of the race1, and the maximum suggestions include that training guid- sprint running velocity of sprinters who run ance instructing sprinters to actively 100m in less than 10 seconds is ኑ12.1m/s2. extend the knee and ankle joints of the To achieve such a velocity, a sprinter requires a support leg should be re-evaluated. strong body and efficient running movements.

The 100m final at the 2007 IAAF World Championships in Athletics in Osaka featured Introduction a much-anticipated duel between two of the fastest sprinters of all time, Tyson Gay (USA) lthough the 100 metres might and the then world record holder Asafa Pow- appear to be an uncomplicated dis- ell (JAM). The race was won by Gay in 9.85 A cipline, the athletes seem only to be seconds, with Powell placed third in 9.96.

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In this study, the running movements of Gay ed three-dimensional coordinates and the and Powell in the top velocity phase of that actual values of the calibration points in the race are analysed and compared to data pre- x, y and z-axis directions was 0.005m, viously obtained2 in order to determine the 0.005m and 0.005m, respectively. The characteristics of the two athletes and identi- three-dimensional coordinates were subject- fy points of advice that might be given to ed to smoothing at 7Hz using the Butter- aspiring athletes and their coaches. worth method.

Methods For comparison, data obtained from men's 100m events in international competitions Two high-speed video cameras (Phantom and official Japanese track and field meetings v4, Vision Research Inc, USA) were placed in were used. In the comparison data, the best the highest row of the spectator stands time was the 9.86 run by Carl Lewis (USA) at above the start line and above the finish line the 1991 IAAF World Championships in Ath- in order to capture the two athletes at the letics in Tokyo. 60m mark of the race. The two were syn- chronised and captured images at 100Hz. Results and Discussion Using motion analysis software (DKH, Tokyo, Japan), the two-dimensional coordinates of Step frequency and step length 24 body points were scanned at 100 fps, Running velocity was determined based and the direct linear transformation method on the distance covered by the body’s cen- (DLT) was used to calculate three-dimen- tre of mass over two steps; the running sional coordinates where the x-axis was the velocity at the measurement point was direction of sprinting, the y-axis the vertical 11.85m/s for Gay and 11.88m/s for Powell. direction perpendicular to the ground, and Figure 1 shows the relationships among the z-axis was the horizontal line parallel to running velocity, step frequency and step the starting line. The error between calculat- length.

Figure 1: Relationships among running velocity, step frequency and step length

40 New Studies in Athletics • no. 2/2008 Mid-phase movements of Tyson Gay and Asafa Powell

Figure 2: Relationships among running velocity and recovery leg movements

According to past data2, the faster the run- mum leg angle (the maximum angle formed ning velocity, the greater the step frequency by the vertical line and the line connecting and the step length. For Gay and Powell, step the hip joint and the lateral malleolus) (Figure frequency was 4.90 and 4.96 steps/s, 2). respectively, and step length was 2.42 and 2.40m, respectively. These numbers mostly According to Ito et al. (1998), running agreed with past data. velocity is not related to maximum thigh angle and maximum leg angle, but the faster Gay is 1.83m tall and Powell is 1.90m tall. the running velocity, the greater the minimum The step length to height ratio for Gay and knee angle. The maximum thigh angle for Powell is 1.32 and 1.26, respectively. Gay and Powell was comparable at 65° and Hence, while Gay can be said to be a step- 70°, respectively; the minimum knee angle length type sprinter, Powell is a step-fre- was 41° and 38°, respectively; and the max- quency type sprinter. When Lewis set the imum leg angle for both sprinters was 34°. then world record of 9.86 in 1991, his step These numbers were similar to the previous- frequency was 4.67 steps/s, his step length ly obtained data2. was 2.53m and his step length-to-height ratio was 1.352. Although the technique of the two sprinters appeared different to the naked eye, there Recovery leg movements were no marked differences in the parameters Leg movements during the recovery measured in the present study. In other phase - when the support leg leaves the words, both sprinters moved their legs for- ground and then is moved forward - were ward without excessively raising the thigh, analysed for maximum thigh angle (the max- thus resulting in relatively low knee height. The imum angle formed by the thigh and the ver- horizontal distance from the toe at the point of tical line), minimum knee angle, and maxi- landing to the body’s centre of mass (this

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Figure 3: Relationships among running velocity and support leg movements relates to the maximum leg angle) for the two exhibited a similar movement whereas the sprinters was 0.31m, and this number is knee extension velocity for Lewis was almost comparable to that for sprinters who run zero2. The results of the present study sug- 100m in 11 seconds3. This tells us that it is gest that sprinting technique has entered a not necessarily good for the foot to land new era. immediately underneath the centre of mass. With regard to knee extension velocity, if Support leg movements the knee joint is fixed like in Lewis, then In the present study, the driving movements 100% of hip extension can be transferred to of the support leg were analysed in terms of drive the leg in the posterior direction, but if the maximum extension velocity of the hip, the knee joint is bent like in Gay and Powell, knee and ankle joints of the support leg dur- hip extension velocity is added to the leg, ing landing (Figure 3). Ito et al. reported that causing the drive velocity of the leg in the while fast sprinters exhibited fast hip exten- posterior direction to exceed 100%. Further- sion and slow knee extension, the maximum more, with a driving movement where the ankle extension velocity did not correlate to knee joint is extended, hip extension velocity running velocity2. However, an interesting find- is absorbed by knee extension velocity, thus ing was seen with maximum knee extension reducing the drive velocity of the leg in the velocity for Gay and Powell. During landing, posterior direction. the knee joint of both sprinters always remained bent. When acceleration force was The maximum hip extension velocity for expressed during the later half of the support Gay and Powell was 774 and 693°/s, and phase, the extension velocity had a negative the maximum ankle extension velocity 664 value: -50°/s for Gay and -68°/s for Powell. and 743°/s, respectively. These values were According to our unpublished data, former mostly comparable to the data obtained by world record holder Maurice Greene (USA) Ito et al.2

42 New Studies in Athletics • no. 2/2008 Mid-phase movements of Tyson Gay and Asafa Powell

Guidance recommendations Training guidance that attempts to increase running velocity by reducing the deceleration The results of the present study show that associated with landing should be re-exam- Gay and Powell are world-class sprinters with ined, because the landing distance for Gay different characteristics in terms of step length and Powell is comparable to that of sprinters and step frequency, and suggest that caution who run 100m in 11 seconds. must be exercised by coaches seeking to strongly correct step frequency and length. What is important here is that Gay and Powell continue to bend the knee of the sup- Past studies have shown that the maximum port leg during the support phase, and train- ankle extension velocity is constant and is not ing guidance that instructs sprinters to active- related to running velocity. This suggests that ly extend the knee and ankle joints of the sup- so-called "snapping" movements are due to port leg should be re-evaluated. the spring-like properties of the muscle-ten- don complex involving the triceps muscle of the calf and the Achilles tendon. In other words, athletes do not consciously extend the Please send all correspondence to: ankle, and guidance should take into account Prof Akira Ito this point. [email protected]

REFERENCES

1. AE, M. & ITO, A. (1992). The men’s 100 meters. New 3. FUKUDA, K. & ITO, A. (2004). Relationship between Studies in Athletics, 7, 1, 47-52. sprint running velocity and changes in the horizontal velocity of the body’s center of gravity during the foot 2. ITO, A.; ICHIKAWA, H.; SAITO, M.; SAGAWA, K.; ITO, contact phase. Japan Journal of Physical Education 49, M. & KOBAYSHI, K. (1998). Relationship between sprint 29-39. In Japanese. running movement and velocity at full speed phase during a 100 m race. Japan Journal of Physical Education 43, 260-273. In Japanese.

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